In the past thirty years a variety of chemical systems for dyeing hair have been developed. The most commercially successful of these has utilized phenylenediamine combined with various couplers and modifiers with hydrogen peroxide as the oxidant. Although this system covers gray well it suffers from three problems: phenylenediamine is a known sensitizer; the hair is damaged by repeated exposure to alkaline peroxide; and the color produced may fade over time to an off shade. Furthermore, p-phenylenediamine is oxidized in the presence of resorcinol by hydrogen peroxide to a mutagen that is percutaneously absorbed. (See: Crebelli, R., Conti, L., Carere, A. and Zito, A. [1981] "Mutagenicity of Commercial p-Phenylenediamine and of an Oxidation Mixture of p-Phenylenediamine and Resorcinol in Salmonella typhimurium TA98" Fd. Cosmet. Toxicol. 19: 79-84.
Related prior art U.S. Pat. No. 4,021,538 concerns a "Method for Producing Pigmentation in Hair or Skin" by use of esters of dopa because of their solubility in both water and lipid solvents. U.S. Pat. No. 4,390,341 concerns a composition for coloring hair or skin which employs, inter alia, acylated dopamine or acylated tyrosine derivatives and omega amino acids. The compositions and processes of the subject invention are neither disclosed nor suggested by known prior art procedures.
At this time in the hair dyeing art it is clear that a need exists for an effective dye composition to change gray hair to a pleasing black, brown or other color. Such a dye composition desirably should be non-mutagenic, non-sensitizing, do minimal to no damage to the hair and skin, and impart a desired color that is stable to repeated washings and weathering. The novel hair dye composition and dyeing process of the subject invention is a distinct improvement over commercially-available hair dyes and processes for using the same.